Serena Williams into semis of the Wimbledon 2016

Her level match after match is rising,” says Serena Williams’ coach, Patrick Mouratoglou. “She’s serving better and better, and moving better and better.”

Mouratoglou, the man who watches Serena’s every swing and tracks her every mood, would know. And it’s hard to argue with him. On Monday and Tuesday, for the first time all tournament, the world No. 1 has been in what veteran Serena watchers like to call “lockdown mode.” Gone are the slow starts, gone are the exasperated reactions and brimming emotions, gone are the rackets sent spinning into photographers’ laps.

Gone, most important, are the tight swings, the unforced errors, and the go-for-broke shot selection. A quiet Serena is a dangerous Serena. As Mouratoglou has been known to tell her, “Stay calm, because when you’re calm, you find solutions.”

In her last two matches, against Svetlana Kuznetsova and Anastasia Pavlyuchenkova, Serena stayed calm and found solutions. In both cases, her Russian opponents played well and at times looked to be capable of pulling off an upset.